1 2config PRINTK_TIME
3 bool "Show timing information on printks"
4 depends on PRINTK
5 help
6 Selecting this option causes time stamps of the printk()
7 messages to be added to the output of the syslog() system
8 call and at the console.
9 10 The timestamp is always recorded internally, and exported
11 to /dev/kmsg. This flag just specifies if the timestamp should
12 be included, not that the timestamp is recorded.
13 14 The behavior is also controlled by the kernel command line
15 parameter printk.time=1. See Documentation/kernel-parameters.txt
16 17config DEFAULT_MESSAGE_LOGLEVEL
18 int "Default message log level (1-7)"
19 range 1 7
20 default "4"
21 help
22 Default log level for printk statements with no specified priority.
23 24 This was hard-coded to KERN_WARNING since at least 2.6.10 but folks
25 that are auditing their logs closely may want to set it to a lower
26 priority.
27 28config ENABLE_WARN_DEPRECATED
29 bool "Enable __deprecated logic"
30 default y
31 help
32 Enable the __deprecated logic in the kernel build.
33 Disable this to suppress the "warning: 'foo' is deprecated
34 (declared at kernel/power/somefile.c:1234)" messages.
35 36config ENABLE_MUST_CHECK
37 bool "Enable __must_check logic"
38 default y
39 help
40 Enable the __must_check logic in the kernel build. Disable this to
41 suppress the "warning: ignoring return value of 'foo', declared with
42 attribute warn_unused_result" messages.
43 44config FRAME_WARN
45 int "Warn for stack frames larger than (needs gcc 4.4)"
46 range 0 8192
47 default 1024 if !64BIT
48 default 2048 if 64BIT
49 help
50 Tell gcc to warn at build time for stack frames larger than this.
51 Setting this too low will cause a lot of warnings.
52 Setting it to 0 disables the warning.
53 Requires gcc 4.4
54 55config MAGIC_SYSRQ
56 bool "Magic SysRq key"
57 depends on !UML
58 help
59 If you say Y here, you will have some control over the system even
60 if the system crashes for example during kernel debugging (e.g., you
61 will be able to flush the buffer cache to disk, reboot the system
62 immediately or dump some status information). This is accomplished
63 by pressing various keys while holding SysRq (Alt+PrintScreen). It
64 also works on a serial console (on PC hardware at least), if you
65 send a BREAK and then within 5 seconds a command keypress. The
66 keys are documented in <file:Documentation/sysrq.txt>. Don't say Y
67 unless you really know what this hack does.
68 69config STRIP_ASM_SYMS
70 bool "Strip assembler-generated symbols during link"
71 default n
72 help
73 Strip internal assembler-generated symbols during a link (symbols
74 that look like '.Lxxx') so they don't pollute the output of
75 get_wchan() and suchlike.
76 77config READABLE_ASM
78 bool "Generate readable assembler code"
79 depends on DEBUG_KERNEL
80 help
81 Disable some compiler optimizations that tend to generate human unreadable
82 assembler output. This may make the kernel slightly slower, but it helps
83 to keep kernel developers who have to stare a lot at assembler listings
84 sane.
85 86config UNUSED_SYMBOLS
87 bool "Enable unused/obsolete exported symbols"
88 default y if X86
89 help
90 Unused but exported symbols make the kernel needlessly bigger. For
91 that reason most of these unused exports will soon be removed. This
92 option is provided temporarily to provide a transition period in case
93 some external kernel module needs one of these symbols anyway. If you
94 encounter such a case in your module, consider if you are actually
95 using the right API. (rationale: since nobody in the kernel is using
96 this in a module, there is a pretty good chance it's actually the
97 wrong interface to use). If you really need the symbol, please send a
98 mail to the linux kernel mailing list mentioning the symbol and why
99 you really need it, and what the merge plan to the mainline kernel for
100 your module is.
101 102config DEBUG_FS
103 bool "Debug Filesystem"
104 help
105 debugfs is a virtual file system that kernel developers use to put
106 debugging files into. Enable this option to be able to read and
107 write to these files.
108 109 For detailed documentation on the debugfs API, see
110 Documentation/DocBook/filesystems.
111 112 If unsure, say N.
113 114config HEADERS_CHECK
115 bool "Run 'make headers_check' when building vmlinux"
116 depends on !UML
117 help
118 This option will extract the user-visible kernel headers whenever
119 building the kernel, and will run basic sanity checks on them to
120 ensure that exported files do not attempt to include files which
121 were not exported, etc.
122 123 If you're making modifications to header files which are
124 relevant for userspace, say 'Y', and check the headers
125 exported to $(INSTALL_HDR_PATH) (usually 'usr/include' in
126 your build tree), to make sure they're suitable.
127 128config DEBUG_SECTION_MISMATCH
129 bool "Enable full Section mismatch analysis"
130 help
131 The section mismatch analysis checks if there are illegal
132 references from one section to another section.
133 During linktime or runtime, some sections are dropped;
134 any use of code/data previously in these sections would
135 most likely result in an oops.
136 In the code, functions and variables are annotated with
137 __init, __devinit, etc. (see the full list in include/linux/init.h),
138 which results in the code/data being placed in specific sections.
139 The section mismatch analysis is always performed after a full
140 kernel build, and enabling this option causes the following
141 additional steps to occur:
142 - Add the option -fno-inline-functions-called-once to gcc commands.
143 When inlining a function annotated with __init in a non-init
144 function, we would lose the section information and thus
145 the analysis would not catch the illegal reference.
146 This option tells gcc to inline less (but it does result in
147 a larger kernel).
148 - Run the section mismatch analysis for each module/built-in.o file.
149 When we run the section mismatch analysis on vmlinux.o, we
150 lose valueble information about where the mismatch was
151 introduced.
152 Running the analysis for each module/built-in.o file
153 tells where the mismatch happens much closer to the
154 source. The drawback is that the same mismatch is
155 reported at least twice.
156 - Enable verbose reporting from modpost in order to help resolve
157 the section mismatches that are reported.
158 159config DEBUG_KERNEL
160 bool "Kernel debugging"
161 help
162 Say Y here if you are developing drivers or trying to debug and
163 identify kernel problems.
164 165config DEBUG_SHIRQ
166 bool "Debug shared IRQ handlers"
167 depends on DEBUG_KERNEL && GENERIC_HARDIRQS
168 help
169 Enable this to generate a spurious interrupt as soon as a shared
170 interrupt handler is registered, and just before one is deregistered.
171 Drivers ought to be able to handle interrupts coming in at those
172 points; some don't and need to be caught.
173 174config LOCKUP_DETECTOR
175 bool "Detect Hard and Soft Lockups"
176 depends on DEBUG_KERNEL && !S390
177 help
178 Say Y here to enable the kernel to act as a watchdog to detect
179 hard and soft lockups.
180 181 Softlockups are bugs that cause the kernel to loop in kernel
182 mode for more than 20 seconds, without giving other tasks a
183 chance to run. The current stack trace is displayed upon
184 detection and the system will stay locked up.
185 186 Hardlockups are bugs that cause the CPU to loop in kernel mode
187 for more than 10 seconds, without letting other interrupts have a
188 chance to run. The current stack trace is displayed upon detection
189 and the system will stay locked up.
190 191 The overhead should be minimal. A periodic hrtimer runs to
192 generate interrupts and kick the watchdog task every 4 seconds.
193 An NMI is generated every 10 seconds or so to check for hardlockups.
194 195 The frequency of hrtimer and NMI events and the soft and hard lockup
196 thresholds can be controlled through the sysctl watchdog_thresh.
197 198config HARDLOCKUP_DETECTOR
199 def_bool LOCKUP_DETECTOR && PERF_EVENTS && HAVE_PERF_EVENTS_NMI && \
200 !HAVE_NMI_WATCHDOG
201 202config BOOTPARAM_HARDLOCKUP_PANIC
203 bool "Panic (Reboot) On Hard Lockups"
204 depends on LOCKUP_DETECTOR
205 help
206 Say Y here to enable the kernel to panic on "hard lockups",
207 which are bugs that cause the kernel to loop in kernel
208 mode with interrupts disabled for more than 10 seconds (configurable
209 using the watchdog_thresh sysctl).
210 211 Say N if unsure.
212 213config BOOTPARAM_HARDLOCKUP_PANIC_VALUE
214 int
215 depends on LOCKUP_DETECTOR
216 range 0 1
217 default 0 if !BOOTPARAM_HARDLOCKUP_PANIC
218 default 1 if BOOTPARAM_HARDLOCKUP_PANIC
219 220config BOOTPARAM_SOFTLOCKUP_PANIC
221 bool "Panic (Reboot) On Soft Lockups"
222 depends on LOCKUP_DETECTOR
223 help
224 Say Y here to enable the kernel to panic on "soft lockups",
225 which are bugs that cause the kernel to loop in kernel
226 mode for more than 20 seconds (configurable using the watchdog_thresh
227 sysctl), without giving other tasks a chance to run.
228 229 The panic can be used in combination with panic_timeout,
230 to cause the system to reboot automatically after a
231 lockup has been detected. This feature is useful for
232 high-availability systems that have uptime guarantees and
233 where a lockup must be resolved ASAP.
234 235 Say N if unsure.
236 237config BOOTPARAM_SOFTLOCKUP_PANIC_VALUE
238 int
239 depends on LOCKUP_DETECTOR
240 range 0 1
241 default 0 if !BOOTPARAM_SOFTLOCKUP_PANIC
242 default 1 if BOOTPARAM_SOFTLOCKUP_PANIC
243 244config PANIC_ON_OOPS
245 bool "Panic on Oops" if EXPERT
246 default n
247 help
248 Say Y here to enable the kernel to panic when it oopses. This
249 has the same effect as setting oops=panic on the kernel command
250 line.
251 252 This feature is useful to ensure that the kernel does not do
253 anything erroneous after an oops which could result in data
254 corruption or other issues.
255 256 Say N if unsure.
257 258config PANIC_ON_OOPS_VALUE
259 int
260 range 0 1
261 default 0 if !PANIC_ON_OOPS
262 default 1 if PANIC_ON_OOPS
263 264config DETECT_HUNG_TASK
265 bool "Detect Hung Tasks"
266 depends on DEBUG_KERNEL
267 default LOCKUP_DETECTOR
268 help
269 Say Y here to enable the kernel to detect "hung tasks",
270 which are bugs that cause the task to be stuck in
271 uninterruptible "D" state indefinitiley.
272 273 When a hung task is detected, the kernel will print the
274 current stack trace (which you should report), but the
275 task will stay in uninterruptible state. If lockdep is
276 enabled then all held locks will also be reported. This
277 feature has negligible overhead.
278 279config DEFAULT_HUNG_TASK_TIMEOUT
280 int "Default timeout for hung task detection (in seconds)"
281 depends on DETECT_HUNG_TASK
282 default 120
283 help
284 This option controls the default timeout (in seconds) used
285 to determine when a task has become non-responsive and should
286 be considered hung.
287 288 It can be adjusted at runtime via the kernel.hung_task_timeout_secs
289 sysctl or by writing a value to
290 /proc/sys/kernel/hung_task_timeout_secs.
291 292 A timeout of 0 disables the check. The default is two minutes.
293 Keeping the default should be fine in most cases.
294 295config BOOTPARAM_HUNG_TASK_PANIC
296 bool "Panic (Reboot) On Hung Tasks"
297 depends on DETECT_HUNG_TASK
298 help
299 Say Y here to enable the kernel to panic on "hung tasks",
300 which are bugs that cause the kernel to leave a task stuck
301 in uninterruptible "D" state.
302 303 The panic can be used in combination with panic_timeout,
304 to cause the system to reboot automatically after a
305 hung task has been detected. This feature is useful for
306 high-availability systems that have uptime guarantees and
307 where a hung tasks must be resolved ASAP.
308 309 Say N if unsure.
310 311config BOOTPARAM_HUNG_TASK_PANIC_VALUE
312 int
313 depends on DETECT_HUNG_TASK
314 range 0 1
315 default 0 if !BOOTPARAM_HUNG_TASK_PANIC
316 default 1 if BOOTPARAM_HUNG_TASK_PANIC
317 318config SCHED_DEBUG
319 bool "Collect scheduler debugging info"
320 depends on DEBUG_KERNEL && PROC_FS
321 default y
322 help
323 If you say Y here, the /proc/sched_debug file will be provided
324 that can help debug the scheduler. The runtime overhead of this
325 option is minimal.
326 327config SCHEDSTATS
328 bool "Collect scheduler statistics"
329 depends on DEBUG_KERNEL && PROC_FS
330 help
331 If you say Y here, additional code will be inserted into the
332 scheduler and related routines to collect statistics about
333 scheduler behavior and provide them in /proc/schedstat. These
334 stats may be useful for both tuning and debugging the scheduler
335 If you aren't debugging the scheduler or trying to tune a specific
336 application, you can say N to avoid the very slight overhead
337 this adds.
338 339config TIMER_STATS
340 bool "Collect kernel timers statistics"
341 depends on DEBUG_KERNEL && PROC_FS
342 help
343 If you say Y here, additional code will be inserted into the
344 timer routines to collect statistics about kernel timers being
345 reprogrammed. The statistics can be read from /proc/timer_stats.
346 The statistics collection is started by writing 1 to /proc/timer_stats,
347 writing 0 stops it. This feature is useful to collect information
348 about timer usage patterns in kernel and userspace. This feature
349 is lightweight if enabled in the kernel config but not activated
350 (it defaults to deactivated on bootup and will only be activated
351 if some application like powertop activates it explicitly).
352 353config DEBUG_OBJECTS
354 bool "Debug object operations"
355 depends on DEBUG_KERNEL
356 help
357 If you say Y here, additional code will be inserted into the
358 kernel to track the life time of various objects and validate
359 the operations on those objects.
360 361config DEBUG_OBJECTS_SELFTEST
362 bool "Debug objects selftest"
363 depends on DEBUG_OBJECTS
364 help
365 This enables the selftest of the object debug code.
366 367config DEBUG_OBJECTS_FREE
368 bool "Debug objects in freed memory"
369 depends on DEBUG_OBJECTS
370 help
371 This enables checks whether a k/v free operation frees an area
372 which contains an object which has not been deactivated
373 properly. This can make kmalloc/kfree-intensive workloads
374 much slower.
375 376config DEBUG_OBJECTS_TIMERS
377 bool "Debug timer objects"
378 depends on DEBUG_OBJECTS
379 help
380 If you say Y here, additional code will be inserted into the
381 timer routines to track the life time of timer objects and
382 validate the timer operations.
383 384config DEBUG_OBJECTS_WORK
385 bool "Debug work objects"
386 depends on DEBUG_OBJECTS
387 help
388 If you say Y here, additional code will be inserted into the
389 work queue routines to track the life time of work objects and
390 validate the work operations.
391 392config DEBUG_OBJECTS_RCU_HEAD
393 bool "Debug RCU callbacks objects"
394 depends on DEBUG_OBJECTS
395 help
396 Enable this to turn on debugging of RCU list heads (call_rcu() usage).
397 398config DEBUG_OBJECTS_PERCPU_COUNTER
399 bool "Debug percpu counter objects"
400 depends on DEBUG_OBJECTS
401 help
402 If you say Y here, additional code will be inserted into the
403 percpu counter routines to track the life time of percpu counter
404 objects and validate the percpu counter operations.
405 406config DEBUG_OBJECTS_ENABLE_DEFAULT
407 int "debug_objects bootup default value (0-1)"
408 range 0 1
409 default "1"
410 depends on DEBUG_OBJECTS
411 help
412 Debug objects boot parameter default value
413 414config DEBUG_SLAB
415 bool "Debug slab memory allocations"
416 depends on DEBUG_KERNEL && SLAB && !KMEMCHECK
417 help
418 Say Y here to have the kernel do limited verification on memory
419 allocation as well as poisoning memory on free to catch use of freed
420 memory. This can make kmalloc/kfree-intensive workloads much slower.
421 422config DEBUG_SLAB_LEAK
423 bool "Memory leak debugging"
424 depends on DEBUG_SLAB
425 426config SLUB_DEBUG_ON
427 bool "SLUB debugging on by default"
428 depends on SLUB && SLUB_DEBUG && !KMEMCHECK
429 default n
430 help
431 Boot with debugging on by default. SLUB boots by default with
432 the runtime debug capabilities switched off. Enabling this is
433 equivalent to specifying the "slub_debug" parameter on boot.
434 There is no support for more fine grained debug control like
435 possible with slub_debug=xxx. SLUB debugging may be switched
436 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
437 "slub_debug=-".
438 439config SLUB_STATS
440 default n
441 bool "Enable SLUB performance statistics"
442 depends on SLUB && SYSFS
443 help
444 SLUB statistics are useful to debug SLUBs allocation behavior in
445 order find ways to optimize the allocator. This should never be
446 enabled for production use since keeping statistics slows down
447 the allocator by a few percentage points. The slabinfo command
448 supports the determination of the most active slabs to figure
449 out which slabs are relevant to a particular load.
450 Try running: slabinfo -DA
451 452config DEBUG_KMEMLEAK
453 bool "Kernel memory leak detector"
454 depends on DEBUG_KERNEL && EXPERIMENTAL && \
455 (X86 || ARM || PPC || MIPS || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE)
456 457 select DEBUG_FS
458 select STACKTRACE if STACKTRACE_SUPPORT
459 select KALLSYMS
460 select CRC32
461 help
462 Say Y here if you want to enable the memory leak
463 detector. The memory allocation/freeing is traced in a way
464 similar to the Boehm's conservative garbage collector, the
465 difference being that the orphan objects are not freed but
466 only shown in /sys/kernel/debug/kmemleak. Enabling this
467 feature will introduce an overhead to memory
468 allocations. See Documentation/kmemleak.txt for more
469 details.
470 471 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
472 of finding leaks due to the slab objects poisoning.
473 474 In order to access the kmemleak file, debugfs needs to be
475 mounted (usually at /sys/kernel/debug).
476 477config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
478 int "Maximum kmemleak early log entries"
479 depends on DEBUG_KMEMLEAK
480 range 200 40000
481 default 400
482 help
483 Kmemleak must track all the memory allocations to avoid
484 reporting false positives. Since memory may be allocated or
485 freed before kmemleak is initialised, an early log buffer is
486 used to store these actions. If kmemleak reports "early log
487 buffer exceeded", please increase this value.
488 489config DEBUG_KMEMLEAK_TEST
490 tristate "Simple test for the kernel memory leak detector"
491 depends on DEBUG_KMEMLEAK && m
492 help
493 This option enables a module that explicitly leaks memory.
494 495 If unsure, say N.
496 497config DEBUG_KMEMLEAK_DEFAULT_OFF
498 bool "Default kmemleak to off"
499 depends on DEBUG_KMEMLEAK
500 help
501 Say Y here to disable kmemleak by default. It can then be enabled
502 on the command line via kmemleak=on.
503 504config DEBUG_PREEMPT
505 bool "Debug preemptible kernel"
506 depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
507 default y
508 help
509 If you say Y here then the kernel will use a debug variant of the
510 commonly used smp_processor_id() function and will print warnings
511 if kernel code uses it in a preemption-unsafe way. Also, the kernel
512 will detect preemption count underflows.
513 514config DEBUG_RT_MUTEXES
515 bool "RT Mutex debugging, deadlock detection"
516 depends on DEBUG_KERNEL && RT_MUTEXES
517 help
518 This allows rt mutex semantics violations and rt mutex related
519 deadlocks (lockups) to be detected and reported automatically.
520 521config DEBUG_PI_LIST
522 bool
523 default y
524 depends on DEBUG_RT_MUTEXES
525 526config RT_MUTEX_TESTER
527 bool "Built-in scriptable tester for rt-mutexes"
528 depends on DEBUG_KERNEL && RT_MUTEXES
529 help
530 This option enables a rt-mutex tester.
531 532config DEBUG_SPINLOCK
533 bool "Spinlock and rw-lock debugging: basic checks"
534 depends on DEBUG_KERNEL
535 select UNINLINE_SPIN_UNLOCK
536 help
537 Say Y here and build SMP to catch missing spinlock initialization
538 and certain other kinds of spinlock errors commonly made. This is
539 best used in conjunction with the NMI watchdog so that spinlock
540 deadlocks are also debuggable.
541 542config DEBUG_MUTEXES
543 bool "Mutex debugging: basic checks"
544 depends on DEBUG_KERNEL
545 help
546 This feature allows mutex semantics violations to be detected and
547 reported.
548 549config DEBUG_LOCK_ALLOC
550 bool "Lock debugging: detect incorrect freeing of live locks"
551 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
552 select DEBUG_SPINLOCK
553 select DEBUG_MUTEXES
554 select LOCKDEP
555 help
556 This feature will check whether any held lock (spinlock, rwlock,
557 mutex or rwsem) is incorrectly freed by the kernel, via any of the
558 memory-freeing routines (kfree(), kmem_cache_free(), free_pages(),
559 vfree(), etc.), whether a live lock is incorrectly reinitialized via
560 spin_lock_init()/mutex_init()/etc., or whether there is any lock
561 held during task exit.
562 563config PROVE_LOCKING
564 bool "Lock debugging: prove locking correctness"
565 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
566 select LOCKDEP
567 select DEBUG_SPINLOCK
568 select DEBUG_MUTEXES
569 select DEBUG_LOCK_ALLOC
570 select TRACE_IRQFLAGS
571 default n
572 help
573 This feature enables the kernel to prove that all locking
574 that occurs in the kernel runtime is mathematically
575 correct: that under no circumstance could an arbitrary (and
576 not yet triggered) combination of observed locking
577 sequences (on an arbitrary number of CPUs, running an
578 arbitrary number of tasks and interrupt contexts) cause a
579 deadlock.
580 581 In short, this feature enables the kernel to report locking
582 related deadlocks before they actually occur.
583 584 The proof does not depend on how hard and complex a
585 deadlock scenario would be to trigger: how many
586 participant CPUs, tasks and irq-contexts would be needed
587 for it to trigger. The proof also does not depend on
588 timing: if a race and a resulting deadlock is possible
589 theoretically (no matter how unlikely the race scenario
590 is), it will be proven so and will immediately be
591 reported by the kernel (once the event is observed that
592 makes the deadlock theoretically possible).
593 594 If a deadlock is impossible (i.e. the locking rules, as
595 observed by the kernel, are mathematically correct), the
596 kernel reports nothing.
597 598 NOTE: this feature can also be enabled for rwlocks, mutexes
599 and rwsems - in which case all dependencies between these
600 different locking variants are observed and mapped too, and
601 the proof of observed correctness is also maintained for an
602 arbitrary combination of these separate locking variants.
603 604 For more details, see Documentation/lockdep-design.txt.
605 606config PROVE_RCU
607 bool "RCU debugging: prove RCU correctness"
608 depends on PROVE_LOCKING
609 default n
610 help
611 This feature enables lockdep extensions that check for correct
612 use of RCU APIs. This is currently under development. Say Y
613 if you want to debug RCU usage or help work on the PROVE_RCU
614 feature.
615 616 Say N if you are unsure.
617 618config PROVE_RCU_REPEATEDLY
619 bool "RCU debugging: don't disable PROVE_RCU on first splat"
620 depends on PROVE_RCU
621 default n
622 help
623 By itself, PROVE_RCU will disable checking upon issuing the
624 first warning (or "splat"). This feature prevents such
625 disabling, allowing multiple RCU-lockdep warnings to be printed
626 on a single reboot.
627 628 Say Y to allow multiple RCU-lockdep warnings per boot.
629 630 Say N if you are unsure.
631 632config SPARSE_RCU_POINTER
633 bool "RCU debugging: sparse-based checks for pointer usage"
634 default n
635 help
636 This feature enables the __rcu sparse annotation for
637 RCU-protected pointers. This annotation will cause sparse
638 to flag any non-RCU used of annotated pointers. This can be
639 helpful when debugging RCU usage. Please note that this feature
640 is not intended to enforce code cleanliness; it is instead merely
641 a debugging aid.
642 643 Say Y to make sparse flag questionable use of RCU-protected pointers
644 645 Say N if you are unsure.
646 647config LOCKDEP
648 bool
649 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
650 select STACKTRACE
651 select FRAME_POINTER if !MIPS && !PPC && !ARM_UNWIND && !S390 && !MICROBLAZE
652 select KALLSYMS
653 select KALLSYMS_ALL
654 655config LOCK_STAT
656 bool "Lock usage statistics"
657 depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
658 select LOCKDEP
659 select DEBUG_SPINLOCK
660 select DEBUG_MUTEXES
661 select DEBUG_LOCK_ALLOC
662 default n
663 help
664 This feature enables tracking lock contention points
665 666 For more details, see Documentation/lockstat.txt
667 668 This also enables lock events required by "perf lock",
669 subcommand of perf.
670 If you want to use "perf lock", you also need to turn on
671 CONFIG_EVENT_TRACING.
672 673 CONFIG_LOCK_STAT defines "contended" and "acquired" lock events.
674 (CONFIG_LOCKDEP defines "acquire" and "release" events.)
675 676config DEBUG_LOCKDEP
677 bool "Lock dependency engine debugging"
678 depends on DEBUG_KERNEL && LOCKDEP
679 help
680 If you say Y here, the lock dependency engine will do
681 additional runtime checks to debug itself, at the price
682 of more runtime overhead.
683 684config TRACE_IRQFLAGS
685 bool
686 help
687 Enables hooks to interrupt enabling and disabling for
688 either tracing or lock debugging.
689 690config DEBUG_ATOMIC_SLEEP
691 bool "Sleep inside atomic section checking"
692 select PREEMPT_COUNT
693 depends on DEBUG_KERNEL
694 help
695 If you say Y here, various routines which may sleep will become very
696 noisy if they are called inside atomic sections: when a spinlock is
697 held, inside an rcu read side critical section, inside preempt disabled
698 sections, inside an interrupt, etc...
699 700config DEBUG_LOCKING_API_SELFTESTS
701 bool "Locking API boot-time self-tests"
702 depends on DEBUG_KERNEL
703 help
704 Say Y here if you want the kernel to run a short self-test during
705 bootup. The self-test checks whether common types of locking bugs
706 are detected by debugging mechanisms or not. (if you disable
707 lock debugging then those bugs wont be detected of course.)
708 The following locking APIs are covered: spinlocks, rwlocks,
709 mutexes and rwsems.
710 711config STACKTRACE
712 bool
713 depends on STACKTRACE_SUPPORT
714 715config DEBUG_STACK_USAGE
716 bool "Stack utilization instrumentation"
717 depends on DEBUG_KERNEL && !IA64 && !PARISC
718 help
719 Enables the display of the minimum amount of free stack which each
720 task has ever had available in the sysrq-T and sysrq-P debug output.
721 722 This option will slow down process creation somewhat.
723 724config DEBUG_KOBJECT
725 bool "kobject debugging"
726 depends on DEBUG_KERNEL
727 help
728 If you say Y here, some extra kobject debugging messages will be sent
729 to the syslog.
730 731config DEBUG_HIGHMEM
732 bool "Highmem debugging"
733 depends on DEBUG_KERNEL && HIGHMEM
734 help
735 This options enables addition error checking for high memory systems.
736 Disable for production systems.
737 738config DEBUG_BUGVERBOSE
739 bool "Verbose BUG() reporting (adds 70K)" if DEBUG_KERNEL && EXPERT
740 depends on BUG
741 depends on ARM || AVR32 || M32R || M68K || SPARC32 || SPARC64 || \
742 FRV || SUPERH || GENERIC_BUG || BLACKFIN || MN10300 || TILE
743 default y
744 help
745 Say Y here to make BUG() panics output the file name and line number
746 of the BUG call as well as the EIP and oops trace. This aids
747 debugging but costs about 70-100K of memory.
748 749config DEBUG_INFO
750 bool "Compile the kernel with debug info"
751 depends on DEBUG_KERNEL
752 help
753 If you say Y here the resulting kernel image will include
754 debugging info resulting in a larger kernel image.
755 This adds debug symbols to the kernel and modules (gcc -g), and
756 is needed if you intend to use kernel crashdump or binary object
757 tools like crash, kgdb, LKCD, gdb, etc on the kernel.
758 Say Y here only if you plan to debug the kernel.
759 760 If unsure, say N.
761 762config DEBUG_INFO_REDUCED
763 bool "Reduce debugging information"
764 depends on DEBUG_INFO
765 help
766 If you say Y here gcc is instructed to generate less debugging
767 information for structure types. This means that tools that
768 need full debugging information (like kgdb or systemtap) won't
769 be happy. But if you merely need debugging information to
770 resolve line numbers there is no loss. Advantage is that
771 build directory object sizes shrink dramatically over a full
772 DEBUG_INFO build and compile times are reduced too.
773 Only works with newer gcc versions.
774 775config DEBUG_VM
776 bool "Debug VM"
777 depends on DEBUG_KERNEL
778 help
779 Enable this to turn on extended checks in the virtual-memory system
780 that may impact performance.
781 782 If unsure, say N.
783 784config DEBUG_VIRTUAL
785 bool "Debug VM translations"
786 depends on DEBUG_KERNEL && X86
787 help
788 Enable some costly sanity checks in virtual to page code. This can
789 catch mistakes with virt_to_page() and friends.
790 791 If unsure, say N.
792 793config DEBUG_NOMMU_REGIONS
794 bool "Debug the global anon/private NOMMU mapping region tree"
795 depends on DEBUG_KERNEL && !MMU
796 help
797 This option causes the global tree of anonymous and private mapping
798 regions to be regularly checked for invalid topology.
799 800config DEBUG_WRITECOUNT
801 bool "Debug filesystem writers count"
802 depends on DEBUG_KERNEL
803 help
804 Enable this to catch wrong use of the writers count in struct
805 vfsmount. This will increase the size of each file struct by
806 32 bits.
807 808 If unsure, say N.
809 810config DEBUG_MEMORY_INIT
811 bool "Debug memory initialisation" if EXPERT
812 default !EXPERT
813 help
814 Enable this for additional checks during memory initialisation.
815 The sanity checks verify aspects of the VM such as the memory model
816 and other information provided by the architecture. Verbose
817 information will be printed at KERN_DEBUG loglevel depending
818 on the mminit_loglevel= command-line option.
819 820 If unsure, say Y
821 822config DEBUG_LIST
823 bool "Debug linked list manipulation"
824 depends on DEBUG_KERNEL
825 help
826 Enable this to turn on extended checks in the linked-list
827 walking routines.
828 829 If unsure, say N.
830 831config TEST_LIST_SORT
832 bool "Linked list sorting test"
833 depends on DEBUG_KERNEL
834 help
835 Enable this to turn on 'list_sort()' function test. This test is
836 executed only once during system boot, so affects only boot time.
837 838 If unsure, say N.
839 840config DEBUG_SG
841 bool "Debug SG table operations"
842 depends on DEBUG_KERNEL
843 help
844 Enable this to turn on checks on scatter-gather tables. This can
845 help find problems with drivers that do not properly initialize
846 their sg tables.
847 848 If unsure, say N.
849 850config DEBUG_NOTIFIERS
851 bool "Debug notifier call chains"
852 depends on DEBUG_KERNEL
853 help
854 Enable this to turn on sanity checking for notifier call chains.
855 This is most useful for kernel developers to make sure that
856 modules properly unregister themselves from notifier chains.
857 This is a relatively cheap check but if you care about maximum
858 performance, say N.
859 860config DEBUG_CREDENTIALS
861 bool "Debug credential management"
862 depends on DEBUG_KERNEL
863 help
864 Enable this to turn on some debug checking for credential
865 management. The additional code keeps track of the number of
866 pointers from task_structs to any given cred struct, and checks to
867 see that this number never exceeds the usage count of the cred
868 struct.
869 870 Furthermore, if SELinux is enabled, this also checks that the
871 security pointer in the cred struct is never seen to be invalid.
872 873 If unsure, say N.
874 875#
876# Select this config option from the architecture Kconfig, if it
877# is preferred to always offer frame pointers as a config
878# option on the architecture (regardless of KERNEL_DEBUG):
879#
880config ARCH_WANT_FRAME_POINTERS
881 bool
882 help
883 884config FRAME_POINTER
885 bool "Compile the kernel with frame pointers"
886 depends on DEBUG_KERNEL && \
887 (CRIS || M68K || FRV || UML || \
888 AVR32 || SUPERH || BLACKFIN || MN10300) || \
889 ARCH_WANT_FRAME_POINTERS
890 default y if (DEBUG_INFO && UML) || ARCH_WANT_FRAME_POINTERS
891 help
892 If you say Y here the resulting kernel image will be slightly
893 larger and slower, but it gives very useful debugging information
894 in case of kernel bugs. (precise oopses/stacktraces/warnings)
895 896config BOOT_PRINTK_DELAY
897 bool "Delay each boot printk message by N milliseconds"
898 depends on DEBUG_KERNEL && PRINTK && GENERIC_CALIBRATE_DELAY
899 help
900 This build option allows you to read kernel boot messages
901 by inserting a short delay after each one. The delay is
902 specified in milliseconds on the kernel command line,
903 using "boot_delay=N".
904 905 It is likely that you would also need to use "lpj=M" to preset
906 the "loops per jiffie" value.
907 See a previous boot log for the "lpj" value to use for your
908 system, and then set "lpj=M" before setting "boot_delay=N".
909 NOTE: Using this option may adversely affect SMP systems.
910 I.e., processors other than the first one may not boot up.
911 BOOT_PRINTK_DELAY also may cause LOCKUP_DETECTOR to detect
912 what it believes to be lockup conditions.
913 914config RCU_TORTURE_TEST
915 tristate "torture tests for RCU"
916 depends on DEBUG_KERNEL
917 default n
918 help
919 This option provides a kernel module that runs torture tests
920 on the RCU infrastructure. The kernel module may be built
921 after the fact on the running kernel to be tested, if desired.
922 923 Say Y here if you want RCU torture tests to be built into
924 the kernel.
925 Say M if you want the RCU torture tests to build as a module.
926 Say N if you are unsure.
927 928config RCU_TORTURE_TEST_RUNNABLE
929 bool "torture tests for RCU runnable by default"
930 depends on RCU_TORTURE_TEST = y
931 default n
932 help
933 This option provides a way to build the RCU torture tests
934 directly into the kernel without them starting up at boot
935 time. You can use /proc/sys/kernel/rcutorture_runnable
936 to manually override this setting. This /proc file is
937 available only when the RCU torture tests have been built
938 into the kernel.
939 940 Say Y here if you want the RCU torture tests to start during
941 boot (you probably don't).
942 Say N here if you want the RCU torture tests to start only
943 after being manually enabled via /proc.
944 945config RCU_CPU_STALL_TIMEOUT
946 int "RCU CPU stall timeout in seconds"
947 depends on TREE_RCU || TREE_PREEMPT_RCU
948 range 3 300
949 default 60
950 help
951 If a given RCU grace period extends more than the specified
952 number of seconds, a CPU stall warning is printed. If the
953 RCU grace period persists, additional CPU stall warnings are
954 printed at more widely spaced intervals.
955 956config RCU_CPU_STALL_VERBOSE
957 bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
958 depends on TREE_PREEMPT_RCU
959 default y
960 help
961 This option causes RCU to printk detailed per-task information
962 for any tasks that are stalling the current RCU grace period.
963 964 Say N if you are unsure.
965 966 Say Y if you want to enable such checks.
967 968config RCU_CPU_STALL_INFO
969 bool "Print additional diagnostics on RCU CPU stall"
970 depends on (TREE_RCU || TREE_PREEMPT_RCU) && DEBUG_KERNEL
971 default n
972 help
973 For each stalled CPU that is aware of the current RCU grace
974 period, print out additional per-CPU diagnostic information
975 regarding scheduling-clock ticks, idle state, and,
976 for RCU_FAST_NO_HZ kernels, idle-entry state.
977 978 Say N if you are unsure.
979 980 Say Y if you want to enable such diagnostics.
981 982config RCU_TRACE
983 bool "Enable tracing for RCU"
984 depends on DEBUG_KERNEL
985 help
986 This option provides tracing in RCU which presents stats
987 in debugfs for debugging RCU implementation.
988 989 Say Y here if you want to enable RCU tracing
990 Say N if you are unsure.
991 992config KPROBES_SANITY_TEST
993 bool "Kprobes sanity tests"
994 depends on DEBUG_KERNEL
995 depends on KPROBES
996 default n
997 help
998 This option provides for testing basic kprobes functionality on
999 boot. A sample kprobe, jprobe and kretprobe are inserted and
1000 verified for functionality.

10011002 Say N if you are unsure.
10031004config BACKTRACE_SELF_TEST
1005 tristate "Self test for the backtrace code"
1006 depends on DEBUG_KERNEL
1007 default n
1008 help
1009 This option provides a kernel module that can be used to test
1010 the kernel stack backtrace code. This option is not useful
1011 for distributions or general kernels, but only for kernel
1012 developers working on architecture code.
10131014 Note that if you want to also test saved backtraces, you will
1015 have to enable STACKTRACE as well.
10161017 Say N if you are unsure.
10181019config DEBUG_BLOCK_EXT_DEVT
1020 bool "Force extended block device numbers and spread them"
1021 depends on DEBUG_KERNEL
1022 depends on BLOCK
1023 default n
1024 help
1025 BIG FAT WARNING: ENABLING THIS OPTION MIGHT BREAK BOOTING ON
1026 SOME DISTRIBUTIONS. DO NOT ENABLE THIS UNLESS YOU KNOW WHAT
1027 YOU ARE DOING. Distros, please enable this and fix whatever
1028 is broken.
10291030 Conventionally, block device numbers are allocated from
1031 predetermined contiguous area. However, extended block area
1032 may introduce non-contiguous block device numbers. This
1033 option forces most block device numbers to be allocated from
1034 the extended space and spreads them to discover kernel or
1035 userland code paths which assume predetermined contiguous
1036 device number allocation.
10371038 Note that turning on this debug option shuffles all the
1039 device numbers for all IDE and SCSI devices including libata
1040 ones, so root partition specified using device number
1041 directly (via rdev or root=MAJ:MIN) won't work anymore.
1042 Textual device names (root=/dev/sdXn) will continue to work.
10431044 Say N if you are unsure.
10451046config DEBUG_FORCE_WEAK_PER_CPU
1047 bool "Force weak per-cpu definitions"
1048 depends on DEBUG_KERNEL
1049 help
1050 s390 and alpha require percpu variables in modules to be
1051 defined weak to work around addressing range issue which
1052 puts the following two restrictions on percpu variable
1053 definitions.
10541055 1. percpu symbols must be unique whether static or not
1056 2. percpu variables can't be defined inside a function
10571058 To ensure that generic code follows the above rules, this
1059 option forces all percpu variables to be defined as weak.
10601061config DEBUG_PER_CPU_MAPS
1062 bool "Debug access to per_cpu maps"
1063 depends on DEBUG_KERNEL
1064 depends on SMP
1065 help
1066 Say Y to verify that the per_cpu map being accessed has
1067 been set up. This adds a fair amount of code to kernel memory
1068 and decreases performance.
10691070 Say N if unsure.
10711072config LKDTM
1073 tristate "Linux Kernel Dump Test Tool Module"
1074 depends on DEBUG_FS
1075 depends on BLOCK
1076 default n
1077 help
1078 This module enables testing of the different dumping mechanisms by
1079 inducing system failures at predefined crash points.
1080 If you don't need it: say N
1081 Choose M here to compile this code as a module. The module will be
1082 called lkdtm.
10831084 Documentation on how to use the module can be found in
1085 Documentation/fault-injection/provoke-crashes.txt
10861087config NOTIFIER_ERROR_INJECTION
1088 tristate "Notifier error injection"
1089 depends on DEBUG_KERNEL
1090 select DEBUG_FS
1091 help
1092 This option provides the ability to inject artifical errors to
1093 specified notifier chain callbacks. It is useful to test the error
1094 handling of notifier call chain failures.
10951096 Say N if unsure.
10971098config CPU_NOTIFIER_ERROR_INJECT
1099 tristate "CPU notifier error injection module"
1100 depends on HOTPLUG_CPU && NOTIFIER_ERROR_INJECTION
1101 help
1102 This option provides a kernel module that can be used to test
1103 the error handling of the cpu notifiers by injecting artifical
1104 errors to CPU notifier chain callbacks. It is controlled through
1105 debugfs interface under /sys/kernel/debug/notifier-error-inject/cpu
11061107 If the notifier call chain should be failed with some events
1108 notified, write the error code to "actions/<notifier event>/error".
11091110 Example: Inject CPU offline error (-1 == -EPERM)
11111112 # cd /sys/kernel/debug/notifier-error-inject/cpu
1113 # echo -1 > actions/CPU_DOWN_PREPARE/error
1114 # echo 0 > /sys/devices/system/cpu/cpu1/online
1115 bash: echo: write error: Operation not permitted
11161117 To compile this code as a module, choose M here: the module will
1118 be called cpu-notifier-error-inject.
11191120 If unsure, say N.
11211122config PM_NOTIFIER_ERROR_INJECT
1123 tristate "PM notifier error injection module"
1124 depends on PM && NOTIFIER_ERROR_INJECTION
1125 default m if PM_DEBUG
1126 help
1127 This option provides the ability to inject artifical errors to
1128 PM notifier chain callbacks. It is controlled through debugfs
1129 interface /sys/kernel/debug/notifier-error-inject/pm
11301131 If the notifier call chain should be failed with some events
1132 notified, write the error code to "actions/<notifier event>/error".
11331134 Example: Inject PM suspend error (-12 = -ENOMEM)
11351136 # cd /sys/kernel/debug/notifier-error-inject/pm/
1137 # echo -12 > actions/PM_SUSPEND_PREPARE/error
1138 # echo mem > /sys/power/state
1139 bash: echo: write error: Cannot allocate memory
11401141 To compile this code as a module, choose M here: the module will
1142 be called pm-notifier-error-inject.
11431144 If unsure, say N.
11451146config MEMORY_NOTIFIER_ERROR_INJECT
1147 tristate "Memory hotplug notifier error injection module"
1148 depends on MEMORY_HOTPLUG_SPARSE && NOTIFIER_ERROR_INJECTION
1149 help
1150 This option provides the ability to inject artifical errors to
1151 memory hotplug notifier chain callbacks. It is controlled through
1152 debugfs interface under /sys/kernel/debug/notifier-error-inject/memory
11531154 If the notifier call chain should be failed with some events
1155 notified, write the error code to "actions/<notifier event>/error".
11561157 Example: Inject memory hotplug offline error (-12 == -ENOMEM)
11581159 # cd /sys/kernel/debug/notifier-error-inject/memory
1160 # echo -12 > actions/MEM_GOING_OFFLINE/error
1161 # echo offline > /sys/devices/system/memory/memoryXXX/state
1162 bash: echo: write error: Cannot allocate memory
11631164 To compile this code as a module, choose M here: the module will
1165 be called pSeries-reconfig-notifier-error-inject.
11661167 If unsure, say N.
11681169config PSERIES_RECONFIG_NOTIFIER_ERROR_INJECT
1170 tristate "pSeries reconfig notifier error injection module"
1171 depends on PPC_PSERIES && NOTIFIER_ERROR_INJECTION
1172 help
1173 This option provides the ability to inject artifical errors to
1174 pSeries reconfig notifier chain callbacks. It is controlled
1175 through debugfs interface under
1176 /sys/kernel/debug/notifier-error-inject/pSeries-reconfig/
11771178 If the notifier call chain should be failed with some events
1179 notified, write the error code to "actions/<notifier event>/error".
11801181 To compile this code as a module, choose M here: the module will
1182 be called memory-notifier-error-inject.
11831184 If unsure, say N.
11851186config FAULT_INJECTION
1187 bool "Fault-injection framework"
1188 depends on DEBUG_KERNEL
1189 help
1190 Provide fault-injection framework.
1191 For more details, see Documentation/fault-injection/.
11921193config FAILSLAB
1194 bool "Fault-injection capability for kmalloc"
1195 depends on FAULT_INJECTION
1196 depends on SLAB || SLUB
1197 help
1198 Provide fault-injection capability for kmalloc.
11991200config FAIL_PAGE_ALLOC
1201 bool "Fault-injection capabilitiy for alloc_pages()"
1202 depends on FAULT_INJECTION
1203 help
1204 Provide fault-injection capability for alloc_pages().
12051206config FAIL_MAKE_REQUEST
1207 bool "Fault-injection capability for disk IO"
1208 depends on FAULT_INJECTION && BLOCK
1209 help
1210 Provide fault-injection capability for disk IO.
12111212config FAIL_IO_TIMEOUT
1213 bool "Fault-injection capability for faking disk interrupts"
1214 depends on FAULT_INJECTION && BLOCK
1215 help
1216 Provide fault-injection capability on end IO handling. This
1217 will make the block layer "forget" an interrupt as configured,
1218 thus exercising the error handling.
12191220 Only works with drivers that use the generic timeout handling,
1221 for others it wont do anything.
12221223config FAIL_MMC_REQUEST
1224 bool "Fault-injection capability for MMC IO"
1225 select DEBUG_FS
1226 depends on FAULT_INJECTION && MMC
1227 help
1228 Provide fault-injection capability for MMC IO.
1229 This will make the mmc core return data errors. This is
1230 useful to test the error handling in the mmc block device
1231 and to test how the mmc host driver handles retries from
1232 the block device.
12331234config FAULT_INJECTION_DEBUG_FS
1235 bool "Debugfs entries for fault-injection capabilities"
1236 depends on FAULT_INJECTION && SYSFS && DEBUG_FS
1237 help
1238 Enable configuration of fault-injection capabilities via debugfs.
12391240config FAULT_INJECTION_STACKTRACE_FILTER
1241 bool "stacktrace filter for fault-injection capabilities"
1242 depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
1243 depends on !X86_64
1244 select STACKTRACE
1245 select FRAME_POINTER if !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1246 help
1247 Provide stacktrace filter for fault-injection capabilities
12481249config LATENCYTOP
1250 bool "Latency measuring infrastructure"
1251 depends on HAVE_LATENCYTOP_SUPPORT
1252 depends on DEBUG_KERNEL
1253 depends on STACKTRACE_SUPPORT
1254 depends on PROC_FS
1255 select FRAME_POINTER if !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND
1256 select KALLSYMS
1257 select KALLSYMS_ALL
1258 select STACKTRACE
1259 select SCHEDSTATS
1260 select SCHED_DEBUG
1261 help
1262 Enable this option if you want to use the LatencyTOP tool
1263 to find out which userspace is blocking on what kernel operations.
12641265source mm/Kconfig.debug
1266source kernel/trace/Kconfig
12671268config PROVIDE_OHCI1394_DMA_INIT
1269 bool "Remote debugging over FireWire early on boot"
1270 depends on PCI && X86
1271 help
1272 If you want to debug problems which hang or crash the kernel early
1273 on boot and the crashing machine has a FireWire port, you can use
1274 this feature to remotely access the memory of the crashed machine
1275 over FireWire. This employs remote DMA as part of the OHCI1394
1276 specification which is now the standard for FireWire controllers.
12771278 With remote DMA, you can monitor the printk buffer remotely using
1279 firescope and access all memory below 4GB using fireproxy from gdb.
1280 Even controlling a kernel debugger is possible using remote DMA.
12811282 Usage:
12831284 If ohci1394_dma=early is used as boot parameter, it will initialize
1285 all OHCI1394 controllers which are found in the PCI config space.
12861287 As all changes to the FireWire bus such as enabling and disabling
1288 devices cause a bus reset and thereby disable remote DMA for all
1289 devices, be sure to have the cable plugged and FireWire enabled on
1290 the debugging host before booting the debug target for debugging.
12911292 This code (~1k) is freed after boot. By then, the firewire stack
1293 in charge of the OHCI-1394 controllers should be used instead.
12941295 See Documentation/debugging-via-ohci1394.txt for more information.
12961297config FIREWIRE_OHCI_REMOTE_DMA
1298 bool "Remote debugging over FireWire with firewire-ohci"
1299 depends on FIREWIRE_OHCI
1300 help
1301 This option lets you use the FireWire bus for remote debugging
1302 with help of the firewire-ohci driver. It enables unfiltered
1303 remote DMA in firewire-ohci.
1304 See Documentation/debugging-via-ohci1394.txt for more information.
13051306 If unsure, say N.
13071308config BUILD_DOCSRC
1309 bool "Build targets in Documentation/ tree"
1310 depends on HEADERS_CHECK
1311 help
1312 This option attempts to build objects from the source files in the
1313 kernel Documentation/ tree.
13141315 Say N if you are unsure.
13161317config DYNAMIC_DEBUG
1318 bool "Enable dynamic printk() support"
1319 default n
1320 depends on PRINTK
1321 depends on DEBUG_FS
1322 help
13231324 Compiles debug level messages into the kernel, which would not
1325 otherwise be available at runtime. These messages can then be
1326 enabled/disabled based on various levels of scope - per source file,
1327 function, module, format string, and line number. This mechanism
1328 implicitly compiles in all pr_debug() and dev_dbg() calls, which
1329 enlarges the kernel text size by about 2%.
13301331 If a source file is compiled with DEBUG flag set, any
1332 pr_debug() calls in it are enabled by default, but can be
1333 disabled at runtime as below. Note that DEBUG flag is
1334 turned on by many CONFIG_*DEBUG* options.
13351336 Usage:
13371338 Dynamic debugging is controlled via the 'dynamic_debug/control' file,
1339 which is contained in the 'debugfs' filesystem. Thus, the debugfs
1340 filesystem must first be mounted before making use of this feature.
1341 We refer the control file as: <debugfs>/dynamic_debug/control. This
1342 file contains a list of the debug statements that can be enabled. The
1343 format for each line of the file is:
13441345 filename:lineno [module]function flags format
13461347 filename : source file of the debug statement
1348 lineno : line number of the debug statement
1349 module : module that contains the debug statement
1350 function : function that contains the debug statement
1351 flags : '=p' means the line is turned 'on' for printing
1352 format : the format used for the debug statement
13531354 From a live system:
13551356 nullarbor:~ # cat <debugfs>/dynamic_debug/control
1357 # filename:lineno [module]function flags format
1358 fs/aio.c:222 [aio]__put_ioctx =_ "__put_ioctx:\040freeing\040%p\012"
1359 fs/aio.c:248 [aio]ioctx_alloc =_ "ENOMEM:\040nr_events\040too\040high\012"
1360 fs/aio.c:1770 [aio]sys_io_cancel =_ "calling\040cancel\012"
13611362 Example usage:
13631364 // enable the message at line 1603 of file svcsock.c
1365 nullarbor:~ # echo -n 'file svcsock.c line 1603 +p' >
1366 <debugfs>/dynamic_debug/control
13671368 // enable all the messages in file svcsock.c
1369 nullarbor:~ # echo -n 'file svcsock.c +p' >
1370 <debugfs>/dynamic_debug/control
13711372 // enable all the messages in the NFS server module
1373 nullarbor:~ # echo -n 'module nfsd +p' >
1374 <debugfs>/dynamic_debug/control
13751376 // enable all 12 messages in the function svc_process()
1377 nullarbor:~ # echo -n 'func svc_process +p' >
1378 <debugfs>/dynamic_debug/control
13791380 // disable all 12 messages in the function svc_process()
1381 nullarbor:~ # echo -n 'func svc_process -p' >
1382 <debugfs>/dynamic_debug/control
13831384 See Documentation/dynamic-debug-howto.txt for additional information.
13851386config DMA_API_DEBUG
1387 bool "Enable debugging of DMA-API usage"
1388 depends on HAVE_DMA_API_DEBUG
1389 help
1390 Enable this option to debug the use of the DMA API by device drivers.
1391 With this option you will be able to detect common bugs in device
1392 drivers like double-freeing of DMA mappings or freeing mappings that
1393 were never allocated.
1394 This option causes a performance degredation. Use only if you want
1395 to debug device drivers. If unsure, say N.
13961397config ATOMIC64_SELFTEST
1398 bool "Perform an atomic64_t self-test at boot"
1399 help
1400 Enable this option to test the atomic64_t functions at boot.
14011402 If unsure, say N.
14031404config ASYNC_RAID6_TEST
1405 tristate "Self test for hardware accelerated raid6 recovery"
1406 depends on ASYNC_RAID6_RECOV
1407 select ASYNC_MEMCPY
1408 ---help---
1409 This is a one-shot self test that permutes through the
1410 recovery of all the possible two disk failure scenarios for a
1411 N-disk array. Recovery is performed with the asynchronous
1412 raid6 recovery routines, and will optionally use an offload
1413 engine if one is available.
14141415 If unsure, say N.
14161417source "samples/Kconfig"
14181419source "lib/Kconfig.kgdb"
14201421source "lib/Kconfig.kmemcheck"
14221423config TEST_KSTRTOX
1424 tristate "Test kstrto*() family of functions at runtime"
1425